This invention relates to an expansion joint seal of the type used for sealing an expansion gap against the intrusion of dirt, water and other debris, as for example might be encountered by expansion joints in a pedestrian walkway. More specifically, the present invention relates to an elastomeric expansion seal that may be employed in a joint assembly wherein the seal is connected between a pair of spaced-apart, structural slab members.
One problem encountered with many available expansion joint seals is that the retaining or mounting bead portions become dislodged from one of the slab members or edge element therein over part or all of the longitudinal lengths of the joint with the result that the seal no longer remains watertight and thus, ceases to perform one of the principal functions for which it was provided.
There have been various proposals for the design of seal mounting beads and other approaches to the design of expansion joint seals in general which have had the objective of minimizing the possibility of failure of the joint by dislodging of the seal from the slab members. In regard to expansion seals having mounting beads along the longitudinal edges thereof for mounting in a corresponding cavity of the slab members, a number of specific problems have been encountered. It has been found very difficult in the prior art to form a cavity in a slab member, or edge member element associated with the slab, so that the cavity includes a predetermined cross section with a specified degree of tolerance along the entire length thereof. For example, in extruding a metal edge member with a cavity therein on the order of 16 feet in longitudinal length, it has been found that the extrusion process fails to maintain uniformity in the cross sectional dimensions of the cavity along the entire longitudinal length thereof. On the other hand, it has been found possible in the prior art to maintain a relatively high degree of tolerance with respect to the outer surface cross sectional dimensions of an extruded mounting or retaining bead of an expansion seal. Necessarily, resultant differences in uniformity between the aforesaid seal beads and associated cavities result in the possibility of the bead being more easily dislodged from the edge member. A solution to this problem is disclosed and claimed in U.S. Pat. Nos. 3,994,609 - G. S. Puccio, issued Nov. 30, 1976, 4,018,539 - G. S. Puccio, issued Apr. 19, 1977 and U.S. Ser. No. 702,044 - G. S. Puccio, filed July 2, 1976, now U.S. Pat. No. 4,067,660 all of which are assigned to the assignee of the instant invention.
Another problem encountered in the prior art and overcome by the aforesaid cited references related to the necessity of reducing the size of the mounting bead to permit its insertion into the cavity of an edge member element or slab. A common technique for permitting the reduction in size of the bead was to make it hollow, thereby permitting the bead to be compressed for reception into the retaining cavity of an edge member. Unfortunately, it was found that such prior art hollow beads operated in reverse, and that being subject to compression, they could be easily pulled out of the edge member slab cavity under various conditions, such as water intrusion and freezing.
The present invention incorporates the teachings of the aforesaid references in a seal considered for use primarily in a walkway or concourse situation. Necessarily, the structural slab members forming an outdoor concourse or walkway are subject to expansion and contraction due to environmental conditions as are the slab members forming a road joint, for example. However, in concourse or walkway construction, it is important that the seal not rise above the level of the slab members at any time so as to avoid tripping. In addition, it is desirable that the seal fill the expansion gap between the slabs at a level as close to the top of the slab members as possible so as to avoid, for example, the heels on women's shoes from possibly becoming wedged in the expansion gap.
In addition to the seal filling the gap at a point adjacent to the surfaces of the slab members, it is also desirable that the seal have sufficient strength to withstand vertically applied pressure, such as from women's shoe heels.